The present invention relates generally to a slide locking apparatus for a press mechanism which will economically and expeditiously lock movement of a press slide in any one of a variety of positions.
In the automobile industry, large double action and transfer presses are operated for making a variety of automobile body parts. Such presses, press metal blanks mounted on separate dies into auto parts, such as hoods, side panels, etc. Typically, these presses include a vertically reciprocatable pressing slide which is massive and has, for example, capacities up to thousand of tons of pressure that are exerted on the metal blanks held by the dies. Moreover, the dies themselves can weigh in the order of 40 or 50 tons.
Presently in the automobile industry, it is extremely desirable to produce fewer body parts before a die change is effected, and thus die changes are done more often. In this regard, it is also desirable to minimize production interruption for a die change in normal circumstances. Thus, die changes are desired to be completed fairly quickly and, in some cases, within minutes. Die change procedures, and indeed the art of presses in general, are well-developed. A die is in place on a moving bolster which is in production on the press, while another die is placed on a second moving bolster located outside the press awaiting the next production run. A typical series of steps for changing the dies include removing the production die via the moving bolster, for example an automobile side panel, from the press and, thereafter, then positioning the second moving bolster carrying the hood die into the press. It is, of course, desirable to not only move the die and bolster as promptly as possible, but to avoid the risk of damage to equipment and personnel for failure to secure the press slide adequately. This is often difficult to successfully achieve since the masses involved are considerable. Moreover, during such changes, stringent government mandated safety regulations must be followed to minimize the risk of damage to equipment and personnel. Failure to comply adequately with the safety requirements is not uncommon. One known safety approach utilizes placement of several manually movable safety blocks, between the bottom of a vertically displaceable upper die and the lower die. In practice, the blocks act to prevent damage caused by accidental dropping of the press slide during die maintenance. However, in the work place, it is often the case that workers circumvent these safety rules by not using any or all of these cumbersome safety blocks.
In terms of safety, some modern presses of type described utilize another approach for providing safety during die changes. Specifically, these presses utilize a press slide locking mechanism including a locking gear which when actuated mechanically and directly meshingly locks with a gear on the main drive shaft of a gear train assembly. Accordingly, the latter is in a desired locking position and thus halts the transfer of gear train motion and can lock the press slide in any desired stroke position.
Despite the foregoing, none of the heretofore known prior art approaches relate to adapting a locking mechanism of the last noted type to any one of plurality of double acting and transfer presses which are without such a press locking feature. Accordingly, there is a desire to provide the older presses with safety features of the newer presses in an economical and reliable manner.